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Ladder testing ?
brickmaster1248
Member Posts: 3,344
I am currently loading a "ladder" of rounds with two diferent powders for the 25-06. I have never attempted this so i dont really know what im looking for when i fire these rounds. They way i understand it each individual shot will walk up the"ladder" and there should be a cluster of some sort within the string. Am i correct? Another question i have is about how tall of a string or "ladder" should i expect on the target at 300 yards? Next question i have is after completing one ladder with a certain powder should i completely clean the rifle before starting the next round of testing?
Comments
This is the brief, easier to understand version from LASC:
Creighton Audette et al on Load Development
Bob Fitzgerald, an Old Colony shooter who knows his stuff, once told us that varying the powder charge up or down a little didn't change the elevation of the shots on the target. I tried it and found that Bob was right; half-grain and even full grain increases or decreases in the powder charge made little or no difference on the elevation of the bullet on the target. Sometimes.
Here's the story. With a load that shoots accurately in a given rifle, varying the powder charge up or down a bit does not vary the elevation of the bullets on the target. There are many people who know, or think that they know, why this is. And they're not shy about telling anybody who will listen. I don't know why it is, but I do know that it happens (sometimes) because I've done the experiments.
Turn this around, and we get another approach to load development. If it is possible to vary powder charges around accurate loads without varying elevation; then increasing loads from recommended starting loads should show a range of charges where elevation doesn't vary, and in there is where the accurate load is.
Creighton Audette is credited with devising this approach to load development, it is sometimes called the "Ladder test".
For a purely hypothetical example, let's say we've got a rifle in 297 Blooper and the recommended starting load of LR2468 powder is 10 grains with the 165 grain cast bullet, and maximum is 15 grains. We would load some cartridges with 10, then 10.5, then 11, then ... to maybe 14 grains. We would then shoot some of each at the same target, watching as the bullets struck higher and higher on the target. At some point the elevation would stop increasing, maybe at 13 and 13.5 and 14 grains. With charges over 14 grains the elevation increases-the shots are higher on the paper.
Then we would know that somewhere in here, between 13 and 14 grains, was the most accurate charge, and we would have found this with a minimum amount of shooting and loading.
This is one of the longer and more detailed explanations of the Audette Load Ladder:
http://www.lima-wiederladetechnik.de/Englisch/Laddertest.htm
This is the same file in a .pdf which is easier to store on your computer:
http://www.washtenawsportsmansclub.org/groups/cba/downloads/incredload.pdf
And last and least in my opinion is the Newberry version. Some folks like this method better so read it and compare:
http://optimalchargeweight.embarqspace.com/#/ocwvsladder/4529811360
Best.
He goes by "Green 788" on accuratereloading and predatormasters forums.